Optical and spectroscopic study of a supersonic flowing helium plasma: energy transport in the afterglow.

Flowing plasma jets are increasingly investigated and used for surface treatments, including biological matter, and as soft ionization sources for mass spectrometry. They have the characteristic capability to transport energy from the plasma excitation region to the flowing afterglow, and therefore to a distant application surface, in a controlled manner. The ability to transport and deposit energy into a specimen is related to the actual energy transport mechanism. In case of a flowing helium plasma, the energy in the flowing afterglow may be carried by metastable helium atoms and long-lived helium dimer ions. In this work a systematic investigation of the optical and spectroscopic characteristics of a supersonic flowing helium plasma in vacuum and its afterglow as function of the helium gas density is presented. The experimental data are compared with numerical modeling of the plasma excitation and helium dimer ion formation supported by a Computational Fluid Dynamic simulation of the helium jet. The results indicate that the plasma afterglow is effectively due to helium dimer ions recombination via a three-body reaction.

Dewetting acrylic polymer films with water/propylene carbonate/surfactant mixtures - implications for cultural heritage conservation.

The removal of hydrophobic polymer films from surfaces is one of the top priorities of modern conservation science. Nanostructured fluids containing water, good solvents for polymers, either immiscible or partially miscible with water, and surfactants have been used in the last decade to achieve controlled removal. The dewetting of the polymer film is often an essential step to achieve efficient removal; however, the role of the surfactant throughout the process is yet to be fully understood. We report on the dewetting of a methacrylate/acrylate copolymer film induced by a ternary mixture of water, propylene carbonate (PC) and C9-11E6, a nonionic alcohol ethoxylate surfactant. The fluid microstructure was characterised through small angle X-ray scattering and the interactions between the film and water, water/PC and water/PC/C9-11E6, were monitored through confocal laser-scanning microscopy (CLSM) and analised both from a thermodynamic and a kinetic point of view. The presence of a surfactant is a prerequisite to induce dewetting of µm-thick films at room temperature, but it is not a thermodynamic driver. The amphiphile lowers the interfacial energy between the phases and favors the loss of adhesion of the polymer on glass, decreasing, in turn, the activation energy barrier, which can be overcome by the thermal fluctuations of polymer film stability, initiating the dewetting process.

Note: Real-time monitoring via second-harmonic interferometry of a flow gas cell for laser wakefield acceleration.

The use of a gas cell as a target for laser wakefield acceleration (LWFA) offers the possibility to obtain stable and manageable laser-plasma interaction process, a mandatory condition for practical applications of this emerging technique, especially in multi-stage accelerators. In order to obtain full control of the gas particle number density in the interaction region, thus allowing for a long term stable and manageable LWFA, real-time monitoring is necessary. In fact, the ideal gas law cannot be used to estimate the particle density inside the flow cell based on the preset backing pressure and the room temperature because the gas flow depends on several factors like tubing, regulators, and valves in the gas supply system, as well as vacuum chamber volume and vacuum pump speed/throughput. Here, second-harmonic interferometry is applied to measure the particle number density inside a flow gas cell designed for LWFA. The results demonstrate that real-time monitoring is achieved and that using low backing pressure gas (<1 bar) and different cell orifice diameters (<2 mm) it is possible to finely tune the number density up to the 10(19) cm(-3) range well suited for LWFA.

Investigation on target normal sheath acceleration through measurements of ions energy distribution.

An experimental campaign aiming at investigating the ion acceleration mechanisms through laser-matter interaction in femtosecond domain has been carried out at the Intense Laser Irradiation Laboratory facility with a laser intensity of up to 2 × 10(19) W/cm(2). A Thomson parabola spectrometer was used to obtain the spectra of the ions of the different species accelerated. Here, we show the energy spectra of light-ions and we discuss their dependence on structural characteristics of the target and the role of surface and target bulk in the acceleration process.

Ultrasound-Guided Versus Blind Subacromial Corticosteroid Injections for Subacromial Impingement Syndrome: A Randomized, Double-Blind Clinical Trial.

BACKGROUND: Subacromial corticosteroid injections are frequently performed for impingement syndrome of the shoulder. To improve the accuracy of injections, ultrasound can be used. PURPOSE: To assess the clinical outcome of ultrasound-guided subacromial injections compared with blind subacromial injections for subacromial impingement syndrome. STUDY DESIGN: Randomized controlled clinical trial; Level of evidence, 1. METHODS: A total of 56 shoulders with subacromial impingement syndrome were randomized into 2 groups: 28 shoulders received a subacromial corticosteroid injection with ultrasound guidance (ultrasound group), and 28 shoulders received a subacromial corticosteroid injection without ultrasound guidance (blind group). The visual analog scale (VAS) for pain with overhead activities and the American Shoulder and Elbow Surgeons (ASES) score were obtained before the injection and at 6 weeks after the injection. RESULTS: The VAS score for pain with overhead activities decreased from 59 ± 5 mm (mean ± SEM) before the injection to 33 ± 6 mm at 6 weeks after the injection in the ultrasound group (P < .001) and from 63 ± 4 mm to 39 ± 6 mm, respectively, in the blind group (P < .001). The decrease in the VAS score was not significantly different between the groups (P > .999). The ASES score increased from 57 ± 2 before the injection to 68 ± 3 at 6 weeks after the injection in the ultrasound group (P < .01) and from 54 ± 3 before the injection to 65 ± 4 after the injection in the blind group (P < .01), with no significant difference between the groups (P = .7). Four shoulders (14%) in the ultrasound group and 6 shoulders (21%) in the blind group eventually needed surgery (P = .7). CONCLUSION: No significant differences were found in the clinical outcome when comparing ultrasound-guided subacromial injections to blind subacromial injections for subacromial impingement syndrome. CLINICAL TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN12615000562572.

Note: strain sensitivity comparison between fiber Bragg gratings inscribed on 125 and 80 micron cladding diameter fibers, case study on the solidification monitoring of a photo-curable resin.

The influence of fiber Bragg grating diameter when measuring strain is investigated and quantified. Two fiber Bragg gratings with bare cladding diameter of 125 µm and 80 µm are produced by excimer laser irradiation through a phase mask, and are used to simultaneously monitor the Bragg wavelength shift due to the strain produced by the solidification of a photo-curable resin during light exposure. It is found that the ratio of the measured strains in the two fiber Bragg gratings is close to the inverse ratio of the fiber's cladding diameter. These results represent a direct simultaneous comparison between 125 µm and 80 µm diameter fiber Bragg grating strain sensors, and demonstrate the feasibility of strain measurements in photo-curable resins using bare 80 µm cladding diameter fiber Bragg gratings with an increased sensitivity and spatial resolution compared with standard 125 µm diameter fiber Bragg gratings.

Improved cell activity on biodegradable photopolymer scaffolds using titanate nanotube coatings.

The development of bioactive materials is in the premise of tissue engineering. For several years, surface functionalization of scaffolds has been one of the most promising approaches to stimulate cellular activity and finally improve implant success. Herein, we describe the development of a bioactive composite scaffold composed of a biodegradable photopolymer scaffold and titanate nanotubes (TNTs). The biodegradable photopolymer scaffolds were fabricated by applying mask-projection excimer laser photocuring at 308 nm. TNTs were synthesized and then spin-coated on the porous scaffolds. Upon culturing fibroblast cells on scaffolds, we found that nanotubes coating affects cell viability and proliferation demonstrating that TNT coatings enhance cell growth on the scaffolds by further improving their surface topography.

Engaging communities to develop and sustain comprehensive wellness policies: Louisiana's schools putting prevention to work.

BACKGROUND: Tobacco use, obesity, and physical inactivity among Louisiana's youth pose a serious public health problem. Given the potential of school environments to affect student well-being, the Louisiana Tobacco Control Program developed and tested a pilot program, Schools Putting Prevention to Work. The objective was to assist school districts in developing a comprehensive school wellness policy and engaging their school community to generate environments that support healthful choices and behaviors. COMMUNITY CONTEXT: The pilot was implemented in 27 school districts, reaching an estimated 325,000 people across the state. Demographics of participating students were similar to all Louisiana's public school students. METHODS: A school wellness project state team advised project development. A subgroup that included contractors and partners implemented and modified the pilot. Sites were selected though an application process. Site representatives received trainings, technical assistance, and funding to organize school-based support-building activities and coordinate a school health advisory council to develop policy and sustain healthy school environments. Project sites reported progress monthly; evaluation included data from sites and project administrators. OUTCOME: Twenty-five comprehensive school wellness policies (covering 100% tobacco-free schools and daily physical activity and healthier cafeteria items) were approved by school boards. Environmental changes such as physical activity breaks, healthier vending options, and tobacco-free campuses were adopted. INTERPRETATION: This pilot demonstrated a successful approach to achieving policy and environmental change. The state team engaged and guided school districts to motivate students, parents, faculty/staff/administration, and businesses to establish and maintain opportunities to improve lifestyle health.

Titanate nanotube coatings on biodegradable photopolymer scaffolds.

Rigid, biodegradable photopolymer scaffolds were coated with titanate nanotubes (TNTs) by using a spin-coating method. TNTs were synthesized by a hydrothermal process at 150 °C under 4.7 bar ambient pressure. The biodegradable photopolymer scaffolds were produced by mask-assisted excimer laser photocuring at 308 nm. For scaffold coating, a stable ethanolic TNT sol was prepared by a simple colloid chemical route without the use of any binding compounds or additives. Scanning electron microscopy along with elemental analysis revealed that the scaffolds were homogenously coated by TNTs. The developed TNT coating can further improve the surface geometry of fabricated scaffolds, and therefore it can further increase the cell adhesion.

Laser synthesis of ligand-free bimetallic nanoparticles for plasmonic applications.

A picosecond laser ablation approach has been developed for the synthesis of ligand-free AuAg bimetallic NPs where the relative amount of Ag is controlled in situ through a laser shielding effect. Various measurements, such as optical spectroscopy, transmission electron microscopy combined with energy dispersive X-ray spectroscopy and inductively coupled plasma optical emission spectrometry, revealed the generation of homogenous 15 nm average size bimetallic NPs with different compositions and tunable localized surface plasmon resonance. Furthermore, ligand-free metallic nanoparticles with respect to chemically synthesized nanoparticles display outstanding properties, i.e. featureless Raman background spectrum, which is a basic requirement in many plasmonic applications such as Surface Enhanced Raman Spectroscopy. Various molecules were chemisorbed on the nanoparticle and SERS investigations were carried out, by varying the laser wavelength. The SERS enhancement factor for AuAg bimetallic NPs shows an enhancement factor of about 5.7 × 10(5) with respect to the flat AuAg surface.

Towards excimer-laser-based stereolithography: a rapid process to fabricate rigid biodegradable photopolymer scaffolds.

We demonstrate high-resolution photocross-linking of biodegradable poly(propylene fumarate) (PPF) and diethyl fumarate (DEF) using UV excimer laser photocuring at 308 nm. The curing depth can be tuned in a micrometre range by adjusting the total energy dose (total fluence). Young's moduli of the scaffolds are found to be a few gigapascal, high enough to support bone formation. The results presented here demonstrate that the proposed technique is an excellent tool for the fabrication of stiff and biocompatible structures on a micrometre scale with defined patterns of high resolution in all three spatial dimensions. Using UV laser photocuring at 308 nm will significantly improve the speed of rapid prototyping of biocompatible and biodegradable polymer scaffolds and enables its production in a few seconds, providing high lateral and horizontal resolution. This short timescale is indeed a tremendous asset that will enable a more efficient translation of technology to clinical applications. Preliminary cell tests proved that PPF : DEF scaffolds produced by excimer laser photocuring are biocompatible and, therefore, are promising candidates to be applied in tissue engineering and regenerative medicine.

Tumores de colon de expansión lateral: características en nuestra población / Laterally spreading tumors: characteristics in our population

Introduction: Colorectal cancer is a rising disease worldwide. In Chile, it is the third leading cause of death associated to gastrointestinal cancer. Optimal preventive management requires surveillance of precursor lesions or early-stage tumors. Laterally spreading tumors (LST) are categorized as nonpolypoid colorectal neoplasms. Since there are no demographic data on these lesions in our country, the aim of our study was to describe the characteristics of LSTs based on our department’s data. Methods: We reviewed the department’s colonoscopy database from 1996 to 2006 to obtain clinical, endoscopic and histological data. We excluded patients with family history of polyposis, prior colorectal cancer and inflammatory bowel disease. Results: Out of 3713 colonoscopies performed, 364 (9.8 percent) adenoma cases were detected; 42 (1.2 percent) of them were catalogued as LSTs. Thirty-three LST patients had complete data and were included in the study. The gender proportion was similar between male and female. Ages ranged from 35 and 92 years (mean +/- SD 66.7 +/- 13.7). The tumor size ranged from 10 to 120 mm (mean +/- SD 28.2 +/- 28.3). According to distribution along the large bowel, 19 (57.5 percent) LSTs were located distally and 14 (42.5 percent) were proximal to the splenic flexure. Histology showed 26 adenomas (14 of them with high-grade dysplasia), 5 adenocarcinomas and 2 hyperplastic lesions. Conclusion: In Chile, LSTs are mainly found in the elderly. It is important to detect these lesions because most of them contain cancer or high-grade dysplasia. Therefore, during colonoscopy, we should focus not only on polypoid lesions, but also on flat lesions.

Introducción: El cáncer colorrectal es una enfermedad emergente a nivel mundial. En nuestro país es la tercera causa de muerte por cáncer del tubo digestivo. Un óptimo manejo preventivo implica la detección y tratamiento de las lesiones precursoras y los cánceres incipientes. Los tumores de expansión lateral (Laterally spreading tumors-LST) se consideran lesiones precursoras no polipoídeas. En Chile no existen datos demográficos de estas lesiones, por lo que el objetivo de este estudio es caracterizar los LST en nuestra población. Métodos: Revisamos la base de datos de las colonoscopias realizadas en nuestro Instituto desde 1996 al 2006, obteniendo datos clínicos y las características endoscópicas e histológicas. Excluimos los pacientes con historia de poliposis familiar, cáncer colorrectal y enfermedad inflamatoria intestinal. Resultados: De 3.713 colonoscopias, se detectaron 364 (9,8 por ciento) casos diagnosticados como adenoma, lesiones planas o LST, de los cuales 42 (1,2 por ciento) se catalogaron como LST. Sólo 33 pacientes con LST tenían disponible el estudio histológico. La proporción por género fue similar entre hombres (17) y mujeres (16). El rango de edad se distribuyó entre 35 y 92 años (promedio +/- DE 66,7 +/- 13,7); el tamaño tumoral fue de 10 a 120 mm (promedio +/- DE 28,2 +/- 28,3). De acuerdo a la distribución en el colon y recto, 19 (57,5 por ciento) LST se localizaron distales al ángulo esplénico y 14 (42,5 por ciento) proximales. El estudio histológico demostró 26 adenomas, 14 de los cuales presentaban displasia de alto grado, 5 adenocarcinomas y 2 lesiones hiperplásicas. Conclusión: En nuestra población los LST se presentan mayoritariamente en la tercera edad. Es importante la detección de estas lesiones, dado que en su mayoría contienen un cáncer o son adenomas con displasia de alto grado. Durante la colonoscopia no solamente debemos enfocarnos en los pólipos sino también en las lesiones planas.

Temporal and spatial characterization of a pulsed gas jet by a compact high-speed high-sensitivity second-harmonic interferometer.

A compact modular high-speed high-sensitivity second-harmonic interferometer is used to characterize a pulsed gas jet. The temporal evolution of the line-integrated gas density is measured with a resolution of 1 µs revealing detailed information on its dynamics. The actual radial gas density distribution in the jet is obtained applying the Abel's inversion method. The sensitivity of the interferometer is 1 mrad, and its robustness, compactness and modularity make the instrument suitable for practical application. Possible use of the instrument in monitoring cluster formation, and phase-dispersion microscopy is discussed.

Dynamic formation of a hot field reversed configuration with improved confinement by supersonic merging of two colliding high-ß compact toroids.

A hot stable field-reversed configuration (FRC) has been produced in the C-2 experiment by colliding and merging two high-ß plasmoids preformed by the dynamic version of field-reversed θ-pinch technology. The merging process exhibits the highest poloidal flux amplification obtained in a magnetic confinement system (over tenfold increase). Most of the kinetic energy is converted into thermal energy with total temperature (T{i}+T{e}) exceeding 0.5 keV. The final FRC state exhibits a record FRC lifetime with flux confinement approaching classical values. These findings should have significant implications for fusion research and the physics of magnetic reconnection.

Electron density measurements of a field-reversed configuration plasma using a novel compact ultrastable second-harmonic interferometer.

A compact high-sensitivity second-harmonic interferometer for line-integrated electron density measurements on a large plasma machine is presented. The device is based on a fiber coupled near-infrared continuous-wave Nd:YAG laser and is remotely controlled. The performances of the instrument are tested on the Irvine field-reversed configuration machine, and a sensitivity of few 10(14) cm(-2) in measuring line integrated electron density is demonstrated with a time resolution of a few microseconds. The interferometer is self calibrated, has an impressive stability, and it does not require any further alignment after proper installation. These features make this device a real turn-key system suitable for electron density measurement in large plasma machines.

Retrograde facilitation under midazolam: the role of general and specific interference.

In a double-blind, placebo-controlled experiment that used midazolam, a benzodiazepine that creates temporary amnesia, we compared acquisition and retention of paired associates of different types. Some word pairs were studied before the injection of saline or midazolam, and two lists of word pairs were studied after the injection. Critical comparisons involved retention of pairs that were practiced on all three lists, pairs studied on only one list, and pairs that involved recombining cue and response terms from one list to the next, as a function of drug condition. Previous research with benzodiazepines had found retrograde facilitation for material acquired prior to injection, compared with the control condition. One explanation for this facilitation is that the anterograde amnesia produced by the benzodiazepine frees up the hippocampus to better consolidate previously learned material (Wixted, 2004, 2005). We accounted for a rich data set using a simple computational model that incorporated interference effects (cue overload) at retrieval for both general (experimental context) interference and specific (stimulus term) interference without the need to postulate a role for consolidation. The computational model as an Excel spreadsheet may be downloaded from www.psychonomic.org/archive.

Spectral redshift in harmonic generation from plasma dynamics in the laser focus.

High-precision spectral measurements on the 9th harmonic generated in xenon gas are compared with calculations of the plasma dynamics resulting from multiphoton ionization in the laser focus. For the regime of 300 ps pulses and above-saturation intensities a novel mechanism producing redshifts in the harmonics is uncovered and explained. Ions play a double role: the nonlinear susceptibility of the ions is decisive for the harmonic intensity, while their mutual repulsion and the associated increase of the index of refraction is identified as the cause of the redshift.

High-order harmonic generation yielding tunable extreme-ultraviolet radiation of high spectral purity.

Production of extreme-ultraviolet radiation by high-order harmonic generation is demonstrated to yield unprecedented spectral purity of lambda/Delta lambda=2.5 x 10(5) at wavelengths covering the entire range 40-100 nm. Tunability and sub-cm(-1) bandwidth of the harmonics are demonstrated in recordings of the He (1s4p) and Ar (3p(5)3d') resonance lines at 52.2 and 86.6 nm. Frequency shift of the harmonics due to chirp-induced phenomena are investigated and found to be small, resulting in a frequency accuracy of about 5 x 10(-7) in the domain of extreme-ultraviolet radiation.

[Validity of some urinary tests considered singly or in combination in the study of renal effects of cadmium]. / Validita' di alcuni tests urinari, considerati singolarmente o in associazione, nello studio degli effetti renali del cadmio.

A number of indicators of renal effect (N-acetyl-glucosaminidase, retinol binding protein, beta-2-microglobulin, albuminuria) were measured in 42 cadmium-exposed workers divided into 3 subgroups on the basis of the results of the last 10 years' biological monitoring (less than 3, 3-10, greater than 10 micrograms/l). An increase in the first three indicators was observed, particularly in the third subgroup, which, however, due to the wide dispersion of the values, was not statistically significant by the Kruskal-Wallis test. Taking the indicators singly, the marked increase in RBP and beta-2-microglobulin in the heavily exposed subjects was confirmed, along with an increasing sensitivity for NAG, while albuminuria levels were unchanged. Assessment of the "degree of association" of the altered tests demonstrated that the number and type of "association" varies between the subgroups in relation to the exposure conditions: in the first group there were no associations between the altered tests, whereas there were 2 duplicates in the second and 2 duplicates, 2 triplicates and 3 quadruplicates in the heavily exposed group. In the study of the renal effects of cadmium, it is therefore advisable to use several indicators and assess their behaviour both singly and combined, and also analyse the altered tests on the basis of the number and type of "association".